I think Herrera is just as good (if not better than Oscar). He has a massive work rate, is technically skilled, can score goals, and is defensively very good.

At Chelsea Mourinho picked Oscar as his #10 ahead of Mata because of Oscar's work rate, defensive abilities, and of course his offensive abilities. There is no doubt in my mind that if Mourinho doesn't buy a new #10 our #10 next season will be either Herrera or Rooney. He was a #10 in his last season for Bilbao with great success. And I think he deserves a run of games to show us his qualities at that position.